In semiconductor devices, it is desired to provide a low-resistance contact between an n-type or p-type region and metal. In the case of Si devices, for the same metal, a sum of the potential barriers between the n-type or p-type region and metal is at about 1 eV of the bandgap energy. In this case, it is possible to obtain a sufficiently low contact resistance by sufficiently increasing the amount of dopants in both regions. That is, since the potential barrier is sufficiently low, and dopants are sufficiently introduced and activated, a dual contact with both the n-type region and the p-type region can be easily formed without a difficult problem.
However, in the case of SiC devices, a sum of the potential barriers between the n-type or p-type region and metal is about 3 eV of the bandgap energy. In this regard, in practice, it is necessary to prepare two kinds of separate metal materials for the n-type region and the p-type region for use in the electrode. Currently, it is difficult to provide a dual low-resistance contact with both the n-type region and the p-type region using a single metallic material.
In addition, a long-time high-temperature process is indispensable in order to introduce and activate dopants with a high concentration. This is not practical.